Method for transmitting MBSFN subframe configuration information of neighboring cells

ABSTRACT

A method and an apparatus for transmitting multimedia broadcast single-frequency network (MBSFN) subframe configuration information of neighboring cells in a wireless system is provided. The method comprises: transmitting, by a base station of a serving cell, MBSFN subframe configuration information of the serving cell to a UE which accepts services from the serving cell via a broadcast control channel (BCCH); transmitting information on a subset relationship of MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell to the UE which accepts services from the serving cell via the broadcast control channel (BCCH); performing, by the UE, measurements on the neighboring cells according to the subframe configuration information of the serving cell and the information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of a prior application Ser. No. 13/148,801, filed on Nov. 9, 2011, which is a U.S. National Stage application under 35 U.S.C. §371 of an International application filed on Feb. 9, 2010 and assigned application number PCT/KR2010/000776, which claimed the benefit of a Chinese patent application filed on Feb. 10, 2009 in the Chinese Patent Office and assigned Serial number 200910005875.X and of a Chinese patent application filed on Feb. 11, 2009 in the Chinese Patent Office and assigned Serial number 200910004211.1, the entire disclosure of each of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to wireless communication system, in particular to a method for indicating MBSFN subframe configuration information of neighboring cells and completing signal power measurements on the neighboring cells in a wireless communication system.

BACKGROUND ART

At present, many advanced and matured techniques, like OFDM modulation and MIMO antenna, are applied in wireless technology development. With the incoming completion of standardization of these new wireless techniques, the performance of a wireless network in terms of throughput and delay has been greatly improved. In a new wireless system, the LTE (Long Term Evolution) network technique is a representative wireless technique based on OFDM and MIMO. It is currently supported by many operators and providers.

An LTE system supports Multi-cast data transmission in addition to the conventional Uni-cast data transmission. Specifically, FIG. 1 shows the composition of an LTE physical-layer frame. In an LTE system, a 10 ms-long transmission frame 101 is divided into 10 subframes 102 at an interval of 1 ms. Here, some of the subframes can be defined by the system as subframes for Multi-cast transmission. In the subframes supporting Multi-cast transmission, Uni-cast data can be mixed and transmitted in a specified format with TDM multiplexing.

In an OFDM system, when all cells share a single frequency for transmission, in the edge of each cell, signal enhancement can be gained with subframes in Multi-cast transmission for the same transmission content. Therefore, a system in which multimedia broadcast information is transmitted in Multi-cast service and the cells share a single frequency for transmission is called MBSFN (Multimedia Broadcast Single-frequency network).

In the MBSFN, a user equipment (UE) can obtain MBSFN configuration information of a cell where the UE is located, i.e., specific subframe information on configuration of data transmission in MBSFN mode (subframe number), by reading a broadcast control channel (BCCH). With the system information transmitted via the BCCH, UE can also obtain the MBSFN information on neighboring cells relative to the serving cell. At present, the LTE standard specification has already supported such broadcast of the neighboring cell MBSFN configuration information. In the broadcast information, however, some problem exists in message definition, which tends to make the UE unable to accurately learn about MBSFN configurations of the neighboring cells, and thus unable to accurately obtain a strategy for measuring the signals from the neighboring cells. The present invention is made in view of the above problem.

The LTE system is divided into two types of Frame type 1 (MD) and Frame type 2 (TDD) according to the schemes of TDD and FDD. For these two frames structures, SCH (synchronization channel) is transmitted via the zeroth and the fifth subframes in Frame Type 1, and the SCH is transmitted via the first and the sixth subframes in Frame Type 2. If the MBSFN information of one of the neighboring cells can not be correctly transmitted to the UE in the serving cell, the UE is likely to assume all of the subframes, except the one for SCH transmission, are MBSFN subframes in the neighboring cell. Therefore, the UE can perform signal strength measurement only on the subframes for SCH transmission, which results in a degradation of the performance of signal strength measurement for the neighboring cell The present invention can avoid the above disadvantage by perfecting message definition in the current standard.

SUMMARY

An object of the present invention is to provide a method for indicating MBSFN subframe configuration information of neighboring cells and thus optimizing measurement on the neighboring cells.

To achieve the object mentioned above, a method for transmitting, by a base station, MBSFN subframe configuration information of neighboring cells comprises steps of:

transmitting, by a base station of a serving cell, MBSFN subframe configuration information of the serving cell to a UE which accepts services from the serving cell via a broadcast control channel (BCCH);

transmitting, by the base station of the serving cell, information on a subset relationship of MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell to the UE which accepts services from the serving cell via the broadcast control channel (BCCH);

performing, by the UE, measurements on the neighboring cells according to the subframe configuration information of the serving cell and the information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell.

With the method of the present invention, the UE can learn about the MBSFN subframe configuration information of the neighboring cells in a more accurately manner. Therefore, more subframes can be measured to improve measurement accuracy. Meanwhile, the present invention is based on redefinition of messages in the existing method, and thus no extra signaling overhead will be introduced.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows the basic frame structure of the LTE system;

FIG. 2 shows a method for transmitting, by BS, MBSFN subframe configuration information of neighboring cells to a UE according to a first embodiment;

FIG. 3 shows a process that the BS of the serving cell transmits the MBSFN subframe configuration information of the neighboring cells to the UE in the first embodiment.

DETAILED DESCRIPTION

In the following, detailed descriptions of well-known functions or equipments are omitted, to avoid any redundancy.

Now, the present invention is described with reference to FIG. 2.

At Step 201, a BS of the serving cell transmits the MBSFN subframe configuration information of the serving cell to a UE in the serving cell via a broadcast control channel (BCCH).

At Step 202, the BS of the serving cell transmits to the UE information on a subset relationship of the MBSFN subframe configurations of neighboring cells relative to the MBSFN subframe configuration of the serving cell to the UE in the serving cell.

The above information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell can be transmitted to the UE with Radio Resource Control signaling (RRC signaling) or via the broadcast control channel (BCCH).

According to one implementation of the present embodiment, the information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell is illustrated in Table 1 as follows.

Table 1: Information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell transmitted from the serving cell to the UE

TABLE 1 Description of subframe configuration information of neighboring cells Subframe configurations of neighboring cells: to provide MBSFN subframe configuration information of intra-frequency neighboring cells: 00: MBSFN subframe configurations of some of the neighboring cells are not a subset of the subframe configuration of the serving cell; 10: MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell; 01: No MBSFN subframes are present in all neighbour cells.

According to a further implementation of the present embodiment, the information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell is illustrated in Table 2 as follows.

Table 2: Information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell transmitted from the serving cell to the UE

TABLE 2 Description of subframe configuration information of neighboring cells Subframe configurations of neighboring cells: to provide MBSFN subframe configuration information of intra-frequency neighboring cells: 00: MBSFN subframe configurations of some of the neighboring cells are not a subset of the subframe configuration of the serving cell; 10: MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell; 01: No MBSFN sub frames are present in all neighbour cells.

According to still a further implementation of the present embodiment, the information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell is illustrated in Table 3 as follows.

Table 3: Information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell transmitted from the serving cell to the UE

TABLE 3 Description of subframe configuration information of neighboring cells Subframe configurations of neighboring cells: to provide MBSFN subframe configuration information of intra-frequency neighboring cells and inter-frequency neighboring cells: 00: MBSFN subframe configurations of some of the neighboring cells are not a subset of the subframe configuration of the serving cell; 10: MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell; 01: No MBSFN subframes are present in all neighbour cells.

With the above description of subframe configuration information of neighboring cells, if “no MBSFN subframes are present in all neighbour cells”, the BS of the serving cell transmits “01” to the UE; if “MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell”, the BS of the serving cell transmits “10” to the UE; and if “MBSFN subframe configurations of some of the neighboring cells are not a subset of the subframe configuration of the serving cell”, the BS of the serving cell transmits “00” to the UE.

At Step 203, according to the subframe configuration information of the serving cell and the information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the subframe configuration of the serving cell, the UE implements respective measurements on the neighboring cells.

For an LTE Frame Type 1 system, if information on the subset relationship of the MBSFN subframe configurations of the neighboring cells relative to the MBSFN subframe configuration of the serving cell received by the UE from the BS of the serving cell is “00”, the UE performs measurement on only the subframe #0 or the subframe #5 of the respective neighboring cell; if the subset relationship information is indicated as “10”, the UE performs measurement on the subframes of the neighboring cell that are the same as the measurement subframes of the serving cell; and if the subset relationship information is indicated as “01”, the UE can performs measurement on all subframes of the neighboring cell.

In the present embodiment, the process that the BS of the serving cell transmits the MBSFN subframe configuration information of the neighboring cells to the UE is illustrated in FIG. 3.

As shown in FIG. 3, the MBSFN subframe configuration information of the neighboring cells is transmitted to the UE via the broadcast control channel (BCCH). If none of the neighboring cells is configured with a MBSFN subframe, “01” is transmitted to the UE; if MBSFN subframe configurations of all the neighboring cells are a subset of the subframe configuration of the serving cell, “10” is transmitted to the UE; otherwise, “00” is transmitted to the UE. 

What is claimed is:
 1. A method for receiving multimedia broadcast single-frequency network (MBSFN) subframe configuration information of a neighboring cell by a terminal, the method comprising: receiving, by the terminal, first information on MBSFN subframe configuration of a serving cell from a base station of the serving cell via a broadcast control channel (BCCH), the first information indicating at least one subframe that is reserved for MBSFN in downlink; receiving, by the terminal, second information on neighboring cell configuration from the base station, the second information including information related to MBSFN subframe configuration of at least one neighboring cell relative to the first information of the serving cell; and measuring, by the terminal, a signal of the at least one neighboring cell on a subframe based on the first information and the second information, wherein the MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell, if the second information is set to
 10. 2. The method of claim 1, wherein the at least one neighboring cell is intra-frequency neighboring cell.
 3. The method of claim 1, wherein the at least one neighboring cell is inter-frequency neighboring cell.
 4. The method of claim 1, wherein the second information includes a first value if no MBSFN subframes are present in the at least one neighboring cells, a second value if MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell, and a third value if MBSFN subframe configurations of some of the neighboring cells are not a subset of the subframe configuration of the serving cell.
 5. The method of claim 4, wherein same value is include in the second information in case MBSFN subframe configuration of all the neighboring cells are identical and MBSFN subframe configuration of all the neighboring cells included in the subframe configuration of the serving cell.
 6. The method of claim 4, wherein the subframe for measuring the signal of the at least one neighboring cell are determined based on the second information, wherein, if the second information includes the first value, the subframes associated with the measurement information are preset subframes, wherein, if the second information includes the second value, the subframes associated with the measurement information are subframes of the neighboring cells that are the same as the measurement subframes of the serving cell, and wherein, if the second information includes the third value, the subframes associated with the measurement information are all subframes of the neighboring cells.
 7. The method of claim 1, wherein the second information is received via radio resource control (RRC) signaling.
 8. A terminal for receiving multimedia broadcast single-frequency network (MBSFN) subframe configuration information of a neighboring cell, the terminal comprising: a transceiver configured to transmit and receive a signal; and a controller configured to: receive first information on MBSFN subframe configuration of a serving cell from a base station of the serving cell via a broadcast control channel (BCCH), the first information indicating at least one subframe that is reserved for MBSFN in downlink, receive second information on neighboring cell configuration from the base station, the second information including information related to MBSFN subframe configuration of at least one neighboring cell relative to the first information of the serving cell, and measure a signal of the at least one neighboring cell on a subframe based on the first information and the second information, wherein the MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell, if the second information is set to
 10. 9. The terminal of claim 8, wherein the at least one neighboring cell is intra-frequency neighboring cell.
 10. The terminal of claim 8, wherein the at least one neighboring cell is inter-frequency neighboring cell.
 11. The terminal of claim 8, wherein the second information includes a first value if no MBSFN subframes are present in the at least one neighboring cells, a second value if MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell, and a third value if MBSFN subframe configurations of some of the neighboring cells are not a subset of the subframe configuration of the serving cell.
 12. The terminal of claim 11, wherein same value is include in the second information in case MBSFN subframe configuration of all the neighboring cells are identical and MBSFN subframe configuration of all the neighboring cells included in the subframe configuration of the serving cell.
 13. The terminal of claim 11, wherein the subframe for measuring the signal of the at least one neighboring cell are determined based on the second information, wherein, if the second information includes the first value, the subframes associated with the measurement information are preset subframes, wherein, if the second information includes the second value, the subframes associated with the measurement information are subframes of the neighboring cells that are the same as the measurement subframes of the serving cell, and wherein, if the second information includes the third value, the subframes associated with the measurement information are all subframes of the neighboring cells.
 14. The terminal of claim 8, wherein the second information is received via radio resource control (RRC) signaling.
 15. A method for transmitting multimedia broadcast single-frequency network (MBSFN) subframe configuration information of a neighboring cell by a base station, the method comprising: transmitting, by the base station, first information on MBSFN subframe configuration of a serving cell to a terminal in a serving cell of the base station via a broadcast control channel (BCCH) to a terminal, the first information indicating at least one subframe that is reserved for MBSFN in downlink; transmitting, by the base station, second information on neighboring cell configuration to the terminal, the second information including information related to MBSFN subframe configuration of at least one neighboring cell relative to the first information of the serving cell; and receiving, by the base station, measurement information of the at least one neighboring cells from the terminal, wherein a signal of the at least one neighboring cell on a subframe for the measurement information is measured based on the first information and the second information, and wherein the MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell, if the second information is set to
 10. 16. The method of claim 15, wherein the at least one neighboring cell is intra-frequency neighboring cell.
 17. The method of claim 15, wherein the at least one neighboring cell is inter-frequency neighboring cell.
 18. The method of claim 15, wherein the second information includes a first value if no MBSFN subframes are present in the at least one neighboring cells, a second value if MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell, and a third value if MBSFN subframe configurations of some of the neighboring cells are not a subset of the subframe configuration of the serving cell.
 19. The method of claim 18, wherein same value is include in the second information in case MBSFN subframe configuration of all the neighboring cells are identical and MBSFN subframe configuration of all the neighboring cells included in the subframe configuration of the serving cell.
 20. The method of claim 18, wherein the subframe for measuring the signal of the at least one neighboring cell are determined based on the second information, wherein, if the second information includes the first value, the subframes associated with the measurement information are preset subframes, wherein, if the second information includes the second value, the subframes associated with the measurement information are subframes of the neighboring cells that are the same as the measurement subframes of the serving cell, and wherein, if the second information includes the third value, the subframes associated with the measurement information are all subframes of the neighboring cells.
 21. The method of claim 15, wherein the second information is received via radio resource control (RRC) signaling.
 22. A base station for transmitting multimedia broadcast single-frequency network (MBSFN) subframe configuration information of a neighboring cell, the base station comprising: a transceiver configured to transmit and receive a signal; and a controller configured to: transmit first information on MBSFN subframe configuration of a serving cell to a terminal in a serving cell of the base station via a broadcast control channel (BCCH), the first information indicating at least one subframe that is reserved for MBSFN in downlink, transmit second information on neighboring cell configuration to the terminal, the second information including information related to MBSFN subframe configuration of at least one neighboring cell relative to the first information of the serving cell, and receive measurement information of the at least one neighboring cells from the terminal, wherein a signal of the at least one neighboring cell on a subframe for the measurement information is measured based on the first information and the second information, and wherein the MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell, if the second information is set to
 10. 23. The base station of claim 22, wherein the at least one neighboring cell is intra-frequency neighboring cell.
 24. The base station of claim 22, wherein the at least one neighboring cell is inter-frequency neighboring cell.
 25. The base station of claim 22, wherein the second information includes a first value if no MBSFN subframes are present in the at least one neighboring cells, a second value if MBSFN subframe configurations of all the neighboring cells are subsets of the subframe configuration of the serving cell, and a third value if MBSFN subframe configurations of some of the neighboring cells are not a subset of the subframe configuration of the serving cell.
 26. The base station of claim 25, wherein same value is include in the second information in case MBSFN subframe configuration of all the neighboring cells are identical and MBSFN subframe configuration of all the neighboring cells included in the subframe configuration of the serving cell.
 27. The base station of claim 25, wherein the subframe for measuring the signal of the at least one neighboring cell are determined based on the second information, wherein, if the second information includes the first value, the subframes associated with the measurement information are preset subframes, wherein, if the second information includes the second value, the subframes associated with the measurement information are subframes of the neighboring cells that are the same as the measurement subframes of the serving cell, and wherein, if the second information includes the third value, the subframes associated with the measurement information are all subframes of the neighboring cells.
 28. The base station of claim 22, wherein the second information is received via radio resource control (RRC) signaling. 